Mechanism for driving shafts at variable speed by means of alternating-current motors.



Nok/26,536.V PAIENIED APE. 28, 1903. 0. HOLZ. MEGIIANISM EOE DRIVING SHEETS AT .VARIABLE SPEED BY MEANS 0E ALTEENA'IING GUEEENI MoIoEs.

APYLIOATION FILED AUG. 15, 1902. F0 IODEL.

l) WEI Witnesses. l Inventor. 9% Otto Hol z z5 shaft to be driven thereby, of intermediate 3o primary winding of the auxiliary motor is ox- 35 the driven shaft, I arrange to cut off 'the ex- U'NITED STATES PATENT OFFICE..

)TTO HOLZ, OF SCIIENCTADY, NEW YORK, ASSIGNOR TO- GENERAL ELEC- rlRIC COMPANY, A CORPORATION OF NEW YORK.

MECHANlSM FOR DRlVlNG SHAFTS AT VARIABLE SPEED BY MEANS F ALTERNATlNG-CURRENT MOTORS.

SPECIFICATION forming part of Letters Patent No. 726,536, dated April 28,1903. Application tiled August 15,1902. Serial No. 119,695. (No model.)

To (LIZ whom. it may concern: speed by the main motor 2, which is preferi 13e it known that I, OTTO HOLZ, a citizen of ably an alternating-current induction-motor the United States, residing at Schenectady', of the three-phase type. Sleeved loosely on county of Schenectady, State of New York, the shaft are the two elements of an auxiliary have invented certain new and useful Irninduction-motor, the primary 3 being inde- 55 provementsin Mechanism tor Driving Shafts pendent of the secondary 4. One of these at Variable Speed by Means of Alternatingelements can be clutched to the power-shaft, Current Motors, of which the following is a while the other (in the drawing the secondary) speci iication. is geared by a pinion 5 and spur-gear 6 to the This invention relates to mechanism for driven shaft 7, which may be a car-axle, as 6otransmitting power from a motor to a driven shown. Driven by the shaft 1 in any suitshaft, and especially where the motor runs at able manner is the armature of a direct-cura constant speed, while thespeed of the shaft rent generator 8, whose shunt field-coils'have must vary from full speed to zero. Such a a rheostat 9 in series with them to enable the 5 deviceis of special value when the' motor is output of the generator to be varied at will. 65 an alternating-current electric motor' which The current from this generator is led from the brushes 10 to the primary 3 of the auxilruns at a nearly-constant speed under a varying load. In many cases, such as that o f iary induction-motor by means of brushes 11 and collector-rings 12 on the sleeve 13, caran electric car, it is necessary to stop and :o start frequently, with a demand for large starting torque in order to accelerate speed rapidly. v

'My invention consists in the combination, with amain alternating-current motor and a The auxiliary induction-motor is preferably constructed as follows: The sleeve 13 carries a member 14, having a number of polar extensions, on each of which is mounted a coil 15, theseveral coils being all connected in series and the winding reversed in alternate coils to produce alternate polarities in the extensions. The secondary 4 carries a closedcircuit winding 16, which may be of the wellknown squirrel-cage type. As the primary So winding is energized by a continuous current from the exciter it produces a constant multipolar field, and when this is revolved in proximity to the secondary currents are induced in the winding 16, as in the rotor of an ordinary polyphase induction-motor. The secondary 4 is therefore caused to rotate with the rotating primary 3 ywhen the latter is coupled to the power-shaft mechanism comprising an auxiliary' induction-motor, one of whose elements is driven by the main motor, while the other element is connected with the shaft to be driven. The

cited from a source of direct current, and by varying this vexciting-current the slip of the auxiliary motor is varied and with it the speed of the driven shaft. In order to stop citing-current, check the rotation of the driving member of the auxiliary motor, and then turn on the current again, thereby causing it -to exert a retarding drag on the still-rotating 4o driven member. Means are provided for clutching the driv- 9o The several elements of my mechanism may ing` member of the auxiliary motor to the be variously arranged to produce the desired power-shaft at will. In the drawing the priresult, and while I have shown only one spemary 3 is the driving member, and the clutch ciic arrangement yet I do not wish to be unis a friction-clutch operated electromagnet- 45 derstood as thereby limiting my invention to ically, though any suitable form of clutch 95 that particular construction. may be used. As shown, the sleeve 13 car- 'Ihe accompanying drawing is a sectional ries a disk 17, having a beveled iange 18 'to elevation of mechanism embodying my invenengage with a beveled iiange .19 on a disk 20, tion. Y- splined on the power-shaft and normallyheld 5o The power-shaft 1 is driven at a constant out of engagement with the disk 17 by an roc rying said primary. 7o l lo magnets.

interposed helical spring 21 or otherwise, as may be desired. The spline v22 permits the disk 2O to have a longitudinalA movement on the shaft 1, butcom pels it to rotate therewith.

On one of the disks, preferably'the disk .20, are one or more magnet-coils 23, connected in series and with two lnsulated slip-rings 24 on the hub of the disk. Brushes 25 bear against said rings and convey current to the When energized, .they attract the disk 17 and cause an engagement of the beveled surface, so thatvthe disk 17, hub 13, and primary 3 are compelled to rotate with ythe disk 2Q and power-shaft 1.

The-primary 3 is provided with a brake (indicated as a shoe 26) engaging with the edge of the disk 17. It may be operated in any suitable manner, preferably by an electromagnet 27, adapted to be put in circuit with zo a source of electric current.

The various circuit connections for starting and stopping the driven shaft are effected by suitable switches. I prefer to group them all in one structure, 4so that the several circuit 2; changes may be made in succession by the movement of a single handle. Such a controller is shown in the drawingvhere the leads from the'exciter-brushes 10 are brought to fingers 105, theleads from the primary winding to 3o fingers 11', the leads from the clutch-magnets to fingers and one lead from the brakemagnet to finger 27', the other terminal of said magnet being permanently in circuit with the negative brush'of the exciter. On a suitable controller-cylinder (shown developed in the drawing) are segments 10 coacting with the fingers 10', segments 11a coacting with the lingers 11', segments 25a coacting with the fingers 25', and a segment 27 co- 4: acting with the finger 27'. There are also stepped segments 28a coacting with fingers 28', which are connected with the sections of a resistance 28. The controller is arranged to move either Way from a central off position.

. The operation of the device is as follows: -Suppose the main motor, the power-shaft, and the disk 20 to be rotating at full speed, the other partsy being at rest, and it is desired to 5o start the load. The left-hand set of segments isbrought into contact with the fingers, seuding current simultaneously through thv` primary winding and the clutch-magnets. The

- primary 3 is therefore caused to rotate with thepower-shaft, while the magnetic flux generated by the primary winding induces current in the lsecondary winding and sets up a drag thereon, so that the secondary begins to rotate. Its motion is communicated to the 6o shaft 7 .through the gears 5 6. The excitingcurrent 1s at first rather weak,

. bece-mes stronger, until in the fourth position I of the controller all the resistance is cut out .mary and secondary is very great at startin the current generated in the secondary very large, and thus I obtain good startii torque. The slipquicklylessens as the spe( of the driven shaft increases until at runnin speed the slip is only suicient to cause tl generation of the proper magnetizing-currel in the secondary.' 1 The running speed can l varied at will by shifting the rheostat 9 c cutting in or out the resistance 28, so as t supply more or less current to the primar winding, and thus vary the strength of th field, and consequently the relative speed o carry the load.

Vclutch-magnets.

the primary and secondary necessary to gen erate enough current in the secondary t When it is desired to sto] the driven shaft, the controller is turner backward, gradually cutting off currentfron the primary winding and finally from the This leaves the denergizedprmary revoiving by its own momentum. A continuedbackward movement oi the controllerbrings the right-hand set of segments into circuit. Iu the first position the magnet 27 is energized and applies the brake to the disk 17, which quickly stops the pri- The exciting-current is then turned on again by a f u rthervbackward movement of the controller, energizing the primary more and more strongly until the reaction between the stationary primary andthe still-revolving secondary exerts a powerful retarding effect on. the latter, which is transmitted by the gears to the driven shaft and rapidly slows it down. a

If desired, the apparatus between the main motor and the driven shaft may be used merely at starting, and when running at full speed the primary may be denergized and stopped and the power-shaft connected directly to the driven shaft. This may bedone in a variety of ways. For instance, there may be a clutch 29 splned on the power-shaft and movable by means of a lever 30 into engage- Having thus described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is

a shaft to be driven, of intermediate connecting mechanism comprising two independently-rotatable members, aclosed winding on one of said members, a primary winding on the other of said members, a direct-current the power-shaft, and -means for connecting one member to said power-shaft and the other to the driven shaft.

w 2. The combination with a power-shaft and a shaft to be driven, of lntermediate connectone of said members, a primary winding on the other member, a direct-current exciter for said primary winding driven by the powershaft, means for varying the exciter-current,

exciter for said primary winding driven by I l. The combination with a power-shaft and and means for coupling one of said members tothe poWer-shaftand the other to the driven shaft. y

3. The combination With a power-shaft and a shaft to be driven, of intermediate connecting mechanism comprising two independently-rotatable members, a closed Winding on one of ,said members, a primary Winding on the other member, a source of direct-current for energizing said primary winding, means for connecting one of said members with the power-shaft, a brake for checking the rotation of said member when disconnected from said shaft, and means for connecting the other member with the driven shaft.

4. The combination with a power-shaft, of a main alternating-current motor driving the same at a practically constant speed, a shaft to be driven at varying speeds, intermediate connecting mechanism comprising an auxiliary induction motor having one element geared to the driven shaft and the other adapted tobe connected with the power-shaft, a clutch for effecting said connection, a source of direct current for energizing the primary of said auxiliary motor, a brake for checking the rotation of the driving element of the auxiliary motor, and a device which successively dcnergizes said element, unclutches it from the power-shaft, applies the brake,

at practically constant speed, a shaft to be driven at varying speeds, and intermediate connecting mechanism comprising an auxiliary induction-motor, means for connecting one element of said auxiliary motor With said power-shaft and the other element with the driven shaft, and means for varying the strength of the iield of said auxiliary induction-motor.

6. The combination with a power-shaft, of a shaft to be driven thereby, intermediate connecting mechanism comprising an auxiliary induction motor having one element geared to the shaft to be driven and the other adapted to be connected With the power-shaft, a clutch for eecting said connection, a source o current for energizing the primary member of said auxiliary motor, abrake for check'- ing the rotation of the driving element of the auxiliary motor, and a switch having its contacts constructed and arranged to supply current to energize the clutch and the primary member of driven shaft and to energize the brake and the primary member of said auxiliary motor to check the rotation of the driven shaft.

In witness whereof I hand this 12th day of August, 1902.

l o'rTo noLz.

and again energizes said element. Witnesses:

The combination with a power-shaft, of BENJAMIN B. HULL, an alternating-current motor driving the same ALMA L. MENSCHKE.

said auxiliary motor to operate the i have hereunto set my 6o 

